1. Field of the Invention
This invention relates to key button structures, particularly to key button structures used in a portable electronic device.
2. Description of related art
Many portable electronic devices such as mobile phones, each has a housing with an interior compartment for receiving a printed circuit board (PCB) therein. The mobile phone usually includes a side key assembly on an outer sidewall of the housing, so that user can operate the mobile phone merely by one finger. Typically, the side key assembly includes a key cover and a key cap adhered with the key cover. The key cap is elastic. The key cap can be distorted once an external force exerted thereon, and then restored to its original state by eliminating the external force. The key assembly is disposed in a hole defined on an outer shell of portable electronic device, and a slight gap is defined between the key assembly and the outer shell. If the key assembly is wetted, water and/or vapor may penetrate through the gap into the portable electronic device, thus affecting circuit board of the portable electronic device. In addition, if the dust in the air enters into the portable electronic device through the gap, the performance of the portable electronic device would also be deteriorated.
Therefore, a new key button structure for use in a portable electronic device in order to overcome the above-described shortcomings needs to be provided.